The Sabatier effect: A partially inverted image on a conventional radiograph

Purpose: The core concepts of radiography and photography are similar in many ways. The purpose of this technical note is to highlight a photographic phenomenon, the Sabatier effect, which appeared on a radiograph. A true lateral cephalogram was taken by the film/screen method and processed manually. Accidental light exposure occurred during development, resulting in the formation of a partially inverted image. However, this result could not be repeated by intentional exposure to light. Exposure to light during development is considered a blunder and it is thought to lead to a completely dark image. However, if the light exposure is followed by further development, it leads to the formation of a partially inverted image, and this occurrence is termed as the Sabatier effect. Due to the numerous variables involved, it is very difficult to obtain consistent reversals and this may be the reason for the failure of appearance of the Sabatier effect on the second occasion. An understanding of this concept requires a thorough appreciation of the fundamentals of image processing. This article aims to describe the mechanism of formation of an image with the Sabatier effect.